He4(p,2p)H3reaction at intermediate energies

The ${}_{}{}^4{}_{}{}^{}\mathrm{He}$($p$,$2p$)${}_{}{}^3{}_{}{}^{}\mathrm{H}$ reaction has been studied at 250, 350, and 500 MeV using coplanar symmetric and asymmetric geometries. The data are presented as energy-sharing spectra, coplanar symmetric angular distributions, and quasifree angular distributions. A comparison with distorted wave impulse approximation calculations indicates reasonable agreement for small recoil momenta ($q\lesssim 150$ MeV/c). For larger recoil momenta, the distorted-wave impulse approximation calculations increasingly underestimate the data. The discrepancies are substantially reduced by inclusion of a spin-orbit term in the optical potential used to generate the distorted waves. Improvements of the single particle wave function for the struck nucleon influence the calculations to a lesser degree. The remaining discrepancies at large recoil momenta may, in part, be ascribed to multiple scattering effects and exchange processes not included in the standard distorted-wave impulse approximation.